Heat exchange assemblies for hot air furnace



Oct. 16, 1962 G. H. FIEDLER HEAT EXCHANGE ASSEMBLIES FOR HOT AIR FURNACEFiled Sept. 17, 1958 2 Sheets-Sheet 1 INVENTOR GEORGE H. F/EoLER KM, W ZM Oct. 16, 1962 cs. H. FIEDLER 3,058,457

HEAT EXCHANGE ASSEMBLIES FOR HOT AIR FURNACE Filed Sept. 17, 1958 2Sheets-Sheet 2 1- 7- 5 INVENTOR A GEO/26f H. F/EDLER f x 70 n 72 3-J .'474' 5 55 7&( M 22 ZATTORNEYfi 3,058,457 HEAT EXCHANGE ASSEMBLIES FOR HOTAIR FURNAEE George H. Fiedler, Euclid, Ghio, assignor to HuppCorporation, Cleveland, Ohio, a corporation of Virginia Filed Sept. 17,1958, Ser. No. 761,544 1 Claim. (Cl. 126-91) This invention relates to anovel heat exchanger for use with gas tired burners.

A principal object of the present invention is to provide a novel heatexchanger which is so arranged as to be mounted vertically in aside-by-side relationship with adjacent heat exchangers. In addition toproviding good heating efliciency of the room air directed over theouter surfaces of the heat exchangers, the novel heat exchangers arelightweight, rigid, free from buckling and inexpensive to manufacture.

These and other objects of the invention will become more fully apparentfrom the claim, and from the description when considered in conjunctionwith the appended drawings wherein:

FIGURE 1 is a side elevation view in section of the furnaceincorporating the heat exchangers of the present invention;

FIGURE 2 is a plan view of one stamping of the heat exchanger as it isreceived from the forming die;

FIGURE 3 is an end elevation view in section of the heat exchangerstamping taken along line 3-3 of FIG- URE 2;

FIGURE 4 is an end elevation view in section of the heat exchangerstamping taken along line 4-4 of FIG- URE 2; and

FIGURE 5 is a partial section taken along line 55 of FIGURE 2 showingthe manner by which the heat exchanger members are secured together.

Referring now to FIGURE 1 in the drawings, the furnace of the presentinvention is provided with a front upper side wall panel which containsair admission apertures, which are preferably perforations, and a lowersolid wall panel 12 which are both removable to provide access to theinterior of the furnace from the front. The side walls as well as therear wall 16 are made of aluminized steel. The air flow pattern for thewarm air heating system is from the bottom of the furnace upwardlythrough filter 18, through blower 20 which is driven by electric motor22, and upwardly around the outer surfaces of heat exchangers one ofwhich is shown at 24 through duct opening 28 at the top of the furnace.

In front of the heat exchanger members 24 is an interior front panel 38which as best shown in FIGURE 1 is supported between the upper sideflange 120 on burner box 40 and the lower side flange 122 on fluecollection box 42. Separate burner elements 44 are provided for each ofthe respective heat exchanger members 24.

Each heat exchanger member comprises a pair of substantially identicalstampings such as that shown generally in FIGURE 2. A peripheral flatedge 60 is provided for securing two stampings together in a face-tofacerelationship so that the lower portion along supporting ribs orembossments 62 will provide a burner receiving chamber. Above ribs 62,four horizontally directed reinforcing ribs or embossments 63, 64, 65and 66 are provided. As is most clearly shown in FIGURE 5, embossments6366 extend outwardly to provide an extended surface area to be exposedto the room air which passes upwardly across the outer surface of theheat exchanger members.

At the upper end of each of the heat exchanger stampings asemicylindrical section 70 is provided so that when the two stampingsare placed together, the heat exchanger member will have a substantiallycylindrical up- Patented Get. 16, 1962 ice per flue collection chamberfor connection to flue box 42. The stamping as shown in FIGURE 2 isformed with an enclosed rear wall 72 for the cylindrical upper fluecollection chamber and also with an enclosed front wall 74 which issubsequently removed as will be explained below. In the spaces betweenhorizontal embossments 63-66 and between embossment 66 and cylindricalwall section 70, the flow of combustion products is restricted by thenarrow passageway along walls 76 as shown in FIGURE 4. This passagewayin a preferred embodiment is very narrow, being only about /2 inchbetween the two stampings.

The heat exchange section members 24 are then run through stampingpresses which cut off the front upper portion containing front wall 74starting at the upper end along edge 80, forwardly along edge 82,downwardly along edge 84, rearwardly along edge 86, downwardly alongedge 88 and diagonally along edge 90 to thereby provide a front open end92 which connects the flue collection chambers defined by cylindricalwalls 70 with flue collection box 42. Referring again to FIGURE 2, theforward lower end of the right side heat exchanger stamping is cut alongedges 94, 96, 98, 100, 102 and 104 to provide an open section which fitsonto the top and rear surfaces of burner box 40. No cuts are made on therear side of the stamping which corresponds with the right-hand side ofthe drawing in FIGURE 2 for the right side stamping.

To provide the left side heat exchanger stamping, the cutting press maybe provided with complementary dies which are cut at the top of thestamping along edges 106, 107, 108, 109, 110, 111 and 112, and at thebottom of the stamping along edges 113, 114, 115, 116, 117 and 119. Nocuts are made on the rear side of the stamping which corresponds withthe left-hand side of the drawing in FIGURE 2 for the left sidestamping.

After the heat exchanger stampings are cut into the desired shape,opposing stampings are placed together face to face and a substantiallycontinuous weld is provided around flanges 60 so as to provide a sealwhich prevents extensive escape of combustion products from the interiorof the heat exchanger members 24. Spot welds are provided at asufficient number of dimples 118 to prevent popping and buckling of themembers as the heat exchanger temperature increases or decreases.

As is apparent from the foregoing, only one die for each of the rightside and left side stampings of the heat exchangers 24 is necessary. Thedie includes horizontal embossments 6366 and dimples 118 which are sopositioned that each of the dimples in the heat exchanger stampingsmeets to be welded together. Dimples 118 and the pattern thereof inwelded secure-ment to each other provide a three-fold function ofpreventing oilcanning of the sides of the exchanger under heat andpressure stresses, collectively with the embossments of formingalternate points of restriction and expansion for the combustionproducts, and of lengthening the time of travel of the combustionproducts through the heat exchanger by restricting the volume andvelocity of the flow of combustion products thereby aiding theefficiency of the exchange of heat. The resulting tortuous flow patterncompelling the combustion products to remain in contact with the metalsurface of the heat exchanger walls obviates the necessity of resortingto separate directional or restrictive baflles at the top of the fluesand the consequent added material necessary when employing such bafllesas was conventional practice heretofore.

In assembly, the heat exchanger stampings are first assembled intocomplete heat exchanger members 24 to be available for use in furnacesof a variety of sizes. For a small residential furnace of 75,000 Btuoutput, 3 heat exchanger members are used. In 150,000 Btu. furnaces,

6 heat exchanger members are used. In intermediate furnace sizes, anintermediate number of heat exchangers are used.

Burner box 40 is provided with a front peripheral flange 120 which ismounted to be in substantial alignment with the front flange 122 on fluecollection box 42 as shown in FIGURE 1. Upper surface 124 of burner box40 is provided with a series of semicircular openings having edges 126for receiving the forward cut-out surfaces along edges 94, 96 and 98 ofthe heat exchanger stampings shown in FIGURE 2. In rear wall 128 ofburner box 40, a series of vertically directed openings havingsemicircular bottom edges are provided for receiving the lower surface102 in front of edge 104 on flange 60 of the heat exchanger members.

Bracket 132 is provided to be suitably secured to the lower rear portionof the heat exchangers 24 and to be supported on frame 122 of thefurnace housing as shown in FIGURE 1.

For the assembly of a specific sized furnace, burner box 40 and fluecollection box 42 are selected which have the desired number of openingsfor receiving a corresponding number of heat exchanger members. Thelower rear surfaces of heat exchanger members 24 are connected to besupported in bracket 120 and the unit is then ready for assembly intothe furnace frame. After the furnace assembly is completed, burners 44may be readily inserted into the heat exchangers with bosses supportedin the grooves of brackets 56 on the inner walls of the heat exchangermembers. Suitable space is provided to insert the burners over the gasmanifold 138 and through burner box 40 and the fuel inlet end of gasburner 44 is supported in a conventional manner on a gas manifold.

The burner support provides an arrangement whereby the burners may bepulled out easily for service and may be shipped in place withoutexcessive wired-down provisions for transportation.

At the top of the furnace, there is further provided flue :box 42 whichconnects all of the heat exchanger members to flue 140 which is adjacentfront wall of the furnace. The forward end 84 of flue collectioncylinders 92 of each heat exchanger is secured as by welding to the rearpanel surface of flue collection box 42. Flue pipe 140 is supported onplate 142 which is suitably secured to flange 122 around flue box 42 andto the side walls of the furnace. Flue plate 142 has a front member 144which extends downwardly along the perforated front panel 10 andcontains an inwardly directed lip 146.

Battle 1 48 is positioned directly below the opening of flue 140 andsecured to the furnace side walls in an angular position so as to alsoextend in front of the cylindrical flue chambers 92 in each of the 'heatexchangers. Thus combustion products passing through flue chambers 92are deflected downwardly by the lower surface of baflle plate 148 andthen upwardly between lip 146 and plate 148 to flue 140. A small spaceis provided above the upper end 149 of bafile plate 148 and flue plate142 whereby some direct flow of combustion products to line 140 ispermitted. The perforations in front panel 10 in conjunction With theend of lip 146 and baflie plate 148 in front of flue 140 provide adirect air flow path up the chimney, and also prevent any downdraft frompassing through the heat exchangers and extinguishing the flame.

Beneath baffle 148 is a further b-afile plate 150 which extends fromfront perforated wall 10 back to flange 122 on the lower surface of fluebox 42 and is secured to the furnace side walls. Beneath baflle plate150 air is free to pass through the perforations in front panel 10 toenter through the burner box 40 inside the heat exchange members 24 andmix with the combustion products.

The air to be heated, on the other hand, all enters through filter 18which is in the lower portion of the furnace beneath the heat exchangersand is forced upwardly by blower 20 across the outside surfaces of theheat exchanger members 24 and around the outside of cylindrical walls ofthe flue collection chambers of the heat exchangers to pass through thewarm air duct opening 28 at the top of the furnace.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claim rather than by the foregoing description, and all changeswhich come within the meaning and range of equivalency of the claim aretherefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

In a furnace of the type having separate air flow paths for combustionproducts and for air to be heated thereby, heat exchanger meanscomprising a pair of upright mem bers of sheet metal of substantiallyuniform thickness formed from the same die secured together around theperiphery thereof, said members having their facing walls spaced apartat their lower end to form a chamber for receiving an elongated burnerelement and at an upper end to form a flue outlet chamber, the facingwalls of said members in the space between said chambers beingpositioned closely together to form a relatively narrow passage for saidcombustion products and containing a plurality of spaced, outwardlyprojecting horizontal, nonintersecting embossments, the embossments ofone memher being directly opposite the embossments of the other member,said embossments on each member being separated by substantially flatportions of said facing walls, inwardly projecting dimples in each ofsaid fiat portions along the length thereof between adjacentembossments, the dimples in each flat portion being arranged instaggered relation to the dimples in a next adjacent flat portion, saiddimples of one member being secured to the corresponding dimples of theother member to prevent separation of said members and to providerestriction to the flow of combustion products, said embossments servingas means for reinforcing said members to reduce buckling noise andenhance the heat exchange between combustion products and air outside ofsaid members to be heated.

References Cited in the file of this patent UNITED STATES PATENTS2,292,180 Tuck Aug. 4, 1942 2,464,473 Wessel Mar. 15, 1949 2,594,608Cartter Apr. 29, 1952 2,613,920 Flint Oct. 14, 1952 2,658,504 Jaye etal. Nov. 10, 1953 2,808,047 Jaye et al Oct. 1, 1957 2,866,449 Baeza Dec.30, 1958

